The invention relates to bolt connections between tubular rods and nodes or junctions in three-dimensional frameworks, with one threaded bolt rotatably and within limits axially displaceably seated at the ends of each tubular rod and with an associated drive sleeve non-rotatably fixed to the threaded bolt but within limits axially displaceably mounted to it, the threaded bolt being rotatably insertable into one of the threaded bores of a junction and the drive sleeve being lockable between a beveling at the junction and the end face of hook-up parts at the ends of the tubular rods.
Such a bolt connection is known, for instance, from German Pat. No. 901,955. In order to have the latitude of using on one hand relatively small junctions and on the other to connect numerous tubular rods to them, the hook-up parts to the tubular rods in the known design have been shaped as tapered parts of frusta of cones or pyramids, the front face resting surface of the drive sleeves being of correspondingly small diameters. Because of the tapered ends of the tubular rods and the drive sleeves adapted with their diameters to them, such a bolt connection is capable of withstanding only fairly low bending forces, whereby such connections are unsuitable for instance for single-shell three-dimensional frameworks or single-shell domes, as in addition to the ordinary tension and compression forces there are substantial bending and torsional moments, which must be absorbed by the bolt connections between the tubular rods and the junctions.
The above drawbacks also occur in the screw connection between tubular rods and couplings disclosed by German Pat. No. 912,145, which, while using drive sleeves of relatively large-diameter resting surfaces, nevertheless makes use of tubular rod ends which taper off conically, as already explained above. Even the reinforcing sleeves mounted over the ends of the tubular rods fall short of thereby enhancing the resistance to bending of this known screw connection in such manner as to be suitable for single-shell three-dimensional frameworks. Additionally, these reinforcing sleeves require additional space and practically prohibit using sideways applied power-driven screwdriver devices which are required to tighten highly rigid, bending-resistant screw connections for instance for three-dimensional framework domes.
It is further known as regards three-dimensional frameworks from German Offenlegungschrift No. 2,246,478 how to hook up the tubular rods with full outside diameter, that is without any taper, to spherical junctions. This known design, however, is such that every threaded bolt is welded by its head into the end of a tubular rod, the threaded bolt at the other end of the tubular rod being pressed outwardly for instance by a compression spring and requiring tightening by means of a screwdriver. Such a screw connection, however, is entirely inadequate for single-shell three-dimensional frameworks. Since the end faces of the tubular rods are beveled inwardly, whereby they are seated in a shape-locking manner on the spherical surface of the junction, the bending forces at the rod ends are transmitted to the junction solely by the threaded bolt, the tubular rods being kept on the junctions' surfaces in the manner of a universal joint by means of the threaded bolts.